This is where it starts to get exciting, folks. The future starts now.
Ubuntu is an operating system for the server, the cloud, the desktop, and the mobile device. One single OS. That makes it different from Apple’s OSes (Mac OS X on the desktop, iOS on the mobile) and Microsoft’s current OSes (Windows 8 on the desktop, Windows RT on the mobile, and Windows Server 2012 on the server and in the cloud).
At least that’s the plan. It’s not yet the reality because there isn’t really a shipping Ubuntu for mobile. Sure, there’s lots of preview releases, but only a shipping version is a shipping version.
So what needs to be done before we have full convergence to a single OS?
Well, one of the things Canonical has been working on is a replacement for the venerable X11 display server traditionally used in most GNU/Linux environments. They’re developing something they’ve called Mir, from the Russian мир meaning “world” or “peace” (but not “world peace”) and the name of the Soviet space station, in keeping with a general space-exploration theme in and around Ubuntu, for reasons. It’s also a German language pronoun (first person singular dative case), as in “show me,” because the original architect was a German national. Really, I’m making this up as I go along and if you’re not one of the tl;dr crowd consider yourself appreciated. This new display server has been discussed in great detail elsewhere and is under active development. The important take away is that in order to run effectively on the mobile form factors, the X11 server needs to be replaced.
This is where Unity8 comes in to the picture. You may have read elsewhere about “Unity Next”, which was a working title for the new Unity in the queue. It’s now more formally known as Unity 8, because it supersedes the current Unity 7 as the one single Unity (there can be only one). Unity 8 is designed to run natively on the Mir compositor, fancy term for what X11 called a display server. That’s what will be on the mobile offering, currently dubbed “Ubuntu Touch”. It’s also what will be on the desktop in the fully converged world.
A replacement for X11 is fine for a phone or a tablet and all, but Ubuntu already has a good thing going with the classic GNU/Linux milieu on the desktop, which is heavily dependent on X. We can’t just throw all that away. So, we need an X11 server running on top of the Mir compositor so all those legacy applications folks and grown to know and love will continue to run just like forever. This is where something dubbed Xmir comes in to play: It’s an x.org driver that fits in to the x.org X11 server just like the nVidia, AMD, and Intel drivers do and lets the X11 server run on top of Mir. Cast your gaze at the screencap in this article: you’re seeing Unity 7 running on Mir on Saucy (the clue is the unity-system-compositor line in the process tree seen in the screencap). This is just like magic. And, because accelerated graphics are still a work in progress, it’s mighty slow magic at this pre-release point. Oh, and yes I see the crash reporter running in the process listing. I do these things so you don’t have to.
What we’re going to do for the Saucy Salamander release of Ubuntu is make a Unity8 Desktop preview available for those who want to take it for a test drive. You’re going to be able to choose to have the option of logging in to either a regular Unity7 session with X11 running, or a Unity8 session without X11. And that, folks, is where the excitement starts.